Double ended invertible inserts have been used in cutting tools for internal and external threading and grooving operations. In such systems, a clamp is provided for the tool holder which clamp is located on the top portion of the tool holder thereby removing it from interference with the workpiece.
In such systems, the cutting insert is subjected to high downwardly and laterally extending loads from the workpiece. Because of the rigidity needed for close tolerance operations, it is imperative that the insert be held in the tool holder without play.
One such system presently in use is disclosed in U.S. Pat. No. 3,754,309 (Jones et al). This system uses a diagonal notch machined in a double ended insert and a two legged clamp, one of the legs being secured by a recess in the tool holder and the other leg being of rounded configuration and acting within the diagonal notch. Force is applied to the clamp and, consequently, the insert by the tightening action of a cap screw between the clamp and the tool holder.
Such system is, however, disadvantageous in that it can lead to a loosening of the insert in the pocket thereby necessitating a rework or scrapping of the workpiece. Further, it is essential in such device that the insert be firmly positioned in the holding pocket prior to tightening the clamp. This is so because the point loading caused by the rounded leg of the clamp against the non-precision notch of the insert creates forces that do not necessarily direct the insert into the innermost position within the pocket of the tool holder.